One example of a conventional combination weigher for weighing objects to be weighed, such as detergents and confectionary, comprises weighing hoppers each including two chambers (weighing chambers). By way of example, as shown in FIG. 1, each weighing hopper 4 includes two weighing chambers 4a and 4b which are capable of independently discharging the objects to be weighed. Feeding hoppers 3 are each capable of selectively discharging the objects to be weighed into the weighing chamber 4a or the weighing chamber 4b of the weighing chamber 4 disposed therebelow. In each weighing hopper 4, when the objects to be weighed are fed only to one of the weighing chambers, for example, the weighing chamber 4a, a weight sensor 5 measures a weight of the objects to be weighed inside the weighing chamber 4a, and sends a measured value to a control unit 10. When the objects to be weighed are fed to the other weighing chamber 4b, the weight sensor 5 measures a total weight of the objects to be weighed inside the two weighing chambers 4a and 4b, and sends a measured value to the control unit 10. The control unit 10 calculates the weight of the objects to be weighed inside the weighing chamber 4b by subtracting the weight of the objects to be weighed inside the weighing chamber 4a that has been previously measured, from the total weight of the objects to be weighed inside the two weighing chambers 4a and 4b, and performs combination calculation. The control unit 10 performs the combination calculation based on the weights of the objects to be weighed inside the weighing chambers 4a and 4b of each weighing hopper 4 obtained as described above to determine a combination of the weighing chambers (4a, 4b) which have been fed with the objects to be weighed whose total weight falls within a predetermined weight range. Under control of the control unit 10, the weighing chambers 4a and 4b selected to form the determined combination open their gates to discharge the objects to be weighed onto the collecting chute 6, and the objects to be weighed are accumulated in the collecting hopper 7. Furthermore, the control unit 10 causes the collecting hopper 7 to open its gate to send out the objects to be weighed from inside the collecting hopper 7 to, for example, a packaging machine (not shown).
Since each weighing hopper 4 is thus divided into the two weighing chambers 4a and 4b, five weighing hoppers 4 are needed to achieve performance (weighing precision) substantially equivalent to that of a combination weigher comprising, for example, 10 weighing hoppers which are not divided into two weighing chambers. This makes it possible to decrease the weight sensors 5 which are expensive to half in number.